Disabling email uniqueness requirement please.

Disabe email uniqueness requirement please. I'm at a nonprofit that has people come and go fairly regularly. So in between them we need to return the their extensions to a generic email address. Like when the extension was created. However ringcetnral doesn't allow that once the extension has been configured. Please add this new feature! I do not want to have to keep extensions attached to nonexistent employees and don't have that enough emails use for this purpose.